Adding transformers to the Pico Compressor (and other projects)

Hi all,

I got the PM below from a fellow lab member and I thought I may as well answer in public in case the info is useful to anyone else.  This thread may also serve as a home for this topic in general as it seems to come up quite often.

"I read on a thread that you are a big pico compressor user. I am too. I use it on almost all my mastering and have been getting good results with it. I noticed you mentioned that you have lundahl trafo's on yours.

I wanted to ask you if you could fill me in on the difference? Is it worth having the transformers in there? How is it better? Smoother?

What transfomers did you use? Are they on input and output, or just one of the 2."


So first in specific answer to the question I have used two different Pico comps for my mastering work (both built by Roger)

- the older blue one without A/R controls (this unit has the THAT 1200 receivers on the input and THAT 1646 driving Cinemag CMOQ-2S on the outputs - hardwired)
- the later 2U P3 which Roger built a short run of - this unit also has the THAT 1200s in the input and again 1646 on the output but this time offers Lundahl LL7902s on the outputs which can be bypassed

So, my thoughts on the CMOQ-2S .... I really like this transformer for the balls that it can give a limp sound.  It's not perfect and seems to roll of the top end slightly but in general I like what it does.  I really like it on individual channels and the 2 buss when I'm mixing, the colour is probably too strong for a lot of mastering work.  A couple of times in the early days I went in and hard bypassed the transformers for specific projects to get a cleaner sound.  The ideal of course would be to make them switchable as they are on my P3.

The Lundahl LL7902 in the P3....I am very hard pressed to hear these in action, when I switch them in I hear a slight difference usually for the worse.  My monitoring system at the moment is pretty good - Cranesong Avocet or Prism DA-2 > Parasound JC-1 monoblocks (have some Hypex arriving this week) > PMC MB2.  I guess the end result is that I leave them bypassed.  Roger clearly heard a difference when designing the comp and it was obviously enough to warrant the significant extra spend but I don't hear it.  End result is that I never switch in the Lundahls.

If I had time I would probably pop the hood on the P3 and replace the Lundahls with something coloured (have some Marinair LO1173 and some API 2503 around here).  There also seems to have been a very good reaction to the Carnhills that Roger is using in the newer builds.

Final thoughts....If you are using your Pico comp for mixing and 2 buss work then the transformers work very well IMHO.  For mastering too much colour becomes a bad thing very quickly - making the transformers switchable might by the key here.  As a backdrop to all of this I find the THAT line receivers and output drivers to sound great (or rather have no sound at all), I cannot tell the difference between my P3 in hard bypass or inline with the transformers switched out.

Sorry for the length....

Cheers,
Ruairi

On the SE II there are jumpers before the 1646 where to insert output transformers And why not put them together with a in/out switch. That said, good discussion about the subject in this thread:

http://www.proaudiodesignforum.com/forum/php/viewtopic.php?f=8&t=195&p=1644

Laurent.

Great info! Thanks a lot! 

Yeah, my comments and a few Spectrafoo comparisons live over in that thread.    I was really not a fan of the Cinemag transformer in question; goes to show it's all opinion.  I know people like them for API builds, or did at one time.  I've heard plenty of vintage iron, and the Cinemag just sounded cheap to me.   The Edcors sounded as good or better (measured better), and the difference in price is nothing more than quality control (or lack thereof).  Roger has settled on the Carnhills, mostly, and they do have good headroom and heft.   The Jensen I tried was too clear, and I can imagine how the Lundahl would be the same.   I have no need for the Pico to add more color, given the rest of my chain, so it's not a consideration here.  Bottom line, is you can stick about any sort of good 600:600 on the front or back, or both.  I need to listen to the Carnhills, so I can form an impression.   I like WE 111C's and UTC LS-30's, neither of which invites mounting in a reasonable sized enclosure.   Both work fine as stand alone interface boxes, hooked up when you want that sheen.  

emrr said:

I've heard plenty of vintage iron, and the Cinemag just sounded cheap to me.  

Click to expand...

Hey Doug,

That's the key!  I'm sure if I'd heard some of the other options I'd probably put the CMOQs on the shelf.  To my ears the pairing with the Pico in RMS mode worked well for adding heft and some density to otherwise slightly thin tracks.  If I had time I'd experiment but as it is I barely have time to sleep, speaking of which....

Cheers,
Ruairi

I've had a listen to one of the Carnhill outputs driven by a THAT 1646 (50 ohm source), and it sounds nice.  Has good color and forward heft to the bottom, harmonics are pleasing and classy, nothing strident or smeary.